bike helmets with environmental material,which can be fixed on the head when you are riding bike.We focus on the quality . Vents: 18 air ventsWeight: 250-265gMaterial:Black EPS+PC ShellTechnology: In-MouldRetension system: Head LockComfortable and Removable LinerColors and Patterns Could be Designed According to Customer’s need.Size:S,M .L,XL bikehelmet